In recent years, video servers (or AV (audio and video) servers) which perform nonlinear recording and reproduction by using a random accessable recording medium have come into widespread use in place of sequential (linear) recording and reproduction using a VTR tape. In general, in order to comply with demands for high image quality and sound quality, a video server employed as an equipment in the broadcasting station is required to achieve a high data transfer rate and a large storage capacity for enabling long-time data recording. Thus, material data composed of a plurality of audio-video data are dispersely recorded by using the RAID (Redundant Arrays of Inexpensive Disks) which is comprised of multiple hard disks adapted for time-division recording and reproduction and performs multi-channel simultaneous transmission or multi-channel reproduction of the same material data with lag of the reproduction time. And thereby so-called VOD (video on demand) and NVOD (near video on demand) have been realized.
The video server mentioned above is connected to some other equipment (editor, player, etc) via a network such as LAN (Local Area Network), and provides the audio-video data recorded in a storage device such as a hard disk via said network, or records the audio-video data obtained from an external equipment such as a video tape recording/reproducing device using the VTR tape as a recording medium.
In the case of recording the audio-video data on the video tape in the memory device of the video server mentioned above, it is necessary to receive the video output from the video tape recording/reproducing device and to convert the video output into a file recordable in the video server. Accordingly, it becomes necessary that the video server is equipped with a VTR control system, a video capture circuit and a function of conversion into a file. Furthermore, since the audio-video data from the video tape recording/reproducing device are entered into the video server at a fixed speed, it is requisite that in order to capture the audio-video data, all of the data receiving circuit, the file transferring network and the memory device of the video server for storing the file should keep operating continuously at a fixed transfer speed respectively without any interruption. Consequently, there have been problems in the conventional system, including that the cost is increased and the specification requirements relative to the network and the storage device of the video server are rendered stricter.
Furthermore, in the video tape recording/reproducing device according to the conventional technology, if the audio-video data are to be transmitted at a slow speed asynchronous transmission, the audio-video data are written in the external memory device such as the hard disk at the fixed speed once and then the data are transmitted asynchronously from the hard disk. And such external memory devices have led to the cost increase.
Moreover, in the video tape recording/reproducing device, since it becomes necessary to have a list of files in advance in order to transfer the file to the other terminal on the network. However, in the video tape recording/reproducing device, since the video tape is a sequential access recording medium, it took time for forming, detecting and referring to such list.